function NG = refine(G)
% refine S1Grid
%
% Input
%  G - @S1Grid
% Output
%  G - @S1Grid with double the points
%

NG = G;

for i=1:length(G)
	d = dist(G(i),G(i).points([2:end,1]));
	np = reshape([G(i).points;...
		G(i).points+d/2],1,[]);
	ind = find(d > 2*min(d));
	np(2*ind) = [];
	NG(i).points = np;	
end
